Fluid switch construction having a sealed deformable container partially filled withan electrically conductive, non-wetting fluid



April 6 E. M. WEISS 3, 7

FLUID SWITCH CONSTRUCTION HAVING A sEALED DEFORMABLE CONTAINER PARTIALLY FILLED WITH AN ELECTRICALLY CONDUCTIVE, NON-WETTING FLUID Filed Nov. 19, 1962 5 Sheets-Sheet 1 E? f3 1 E /8 257 l L I 22 f FoRc- //v od/vces INVENTOR. /2 ER W/N M. WE/ss M IZQ WY WM Aprll 6, 1965 E. M. WEISS 3,177,327

FLUID SWITCH CONSTRUCTION HAVING A SEALED DEFORMABLE CONTAINER PARTIALLY FILLED WITH AN ELECTRICALLY CONDUCTIVE, NON-WETTING FLUID Filed Nov. 19, 1962 5 Sheets-Sheet 2 INVENTOR. ERW/N M. WEISS A T TOR/V5 Y5 /d w l mmm ummmm E 3,177,327 ALED DEFORMABLE ELECTRICALLY CONDUCTIVE, NON-WETTING FLUID April 6, 1965 M. WEISS TION HAVING A CONTAINER PARTIALLY FILLED WITH FLUID SWITCH CONSTRUC 5 Shets-Sheet'E Filed Nov. 19, 19 62 INV EN TOR. 5/? WIN M. WE/SS 8 dfm $0M A T TORNEYS April 6, 1965 E. M. WEISS FLUID SWITCH CONSTRUCTION HAVING A SEALED DEFORMABLE CONTAINER PARTIALLY FILLED WITH AN ELECTRICALLY CONDUCTIVE, NON-WETTING FLUID 5 Sheets-Sheet 4 Filed NOV. 19, 1962 INVENTOR. ERW/N M. I'VE/55 Aprll 6, 1965 E. M. WEISS 3,177,327

FLUID SWITCH CONSTRUCTION HAVING A SEALED DEFORMABLE CONTAINER PARTIALLY FILLED WITH AN ELECTRICALLY CONDUCTIVE, NON-WETTING FLUID Filed Nov. 19, 1962 5 Sheets-Sheet 5 32 INVENTOR.

E R W/N M. WE /$5 KMM %0M I A T TORNEYS United States Patent FLUID SWITCH CONSTRUCTION HAVING A SEALED DEFORMABLE CONTAINER PAR- TIALLY FILLED WITH AN ELECTRICALLY CONDUCTIVE, NON-WETTING FLUID Erwin M. Weiss, Chicago, 11]., assignor to Beltone Electronics Corporation, a corporation of Illinois Filed Nov. 19, 1962, Ser. No. 238,486

Claims. (Cl. 200-152) This invention relates generally to electrical switching apparatus, and more particularly to a unique fluid switch construction which is not position sensitive and has the further advantage of eliminating the contact oscillation problem common to prior art mechanical switches.

It will readily be appreciated by those familiar with the art of mechanical switching devices of the type used in electrical circuitry that all such switches inherently have some contact bounce or oscillation at the time a switching action is made. This causes many undesirable contact openings and closures which result in spurious electrical pulses that cannot be tolerated in many applications, such as high speed electronic data processing equipment. Accordingly, in the prior art, special pulse shaping circuits have been required with such mechanical switching devices to eliminate this undesirable characteristic.

It also is known that conventional mechanical switches sutl'er deterioration as a result of the formation of contaminating films on the switch contact structure. Such films are created in unsealed switches by the deposition of dirt and foreign objects normally present in the atmosphere. In the case of hermetically sealed switches, such films are formed as a result of out-gassing from organic components in the switch assembly. Further, where the switch is subjected to a salt water spray environment in the presence of gasses, such as carbon dioxide, oxygen, and sulfur dioxide, a film will form on the switch contacts composed of oxides, sulphides and carbonates of the metal contacts. As a result of the above considerations, the switch is subject to an increase in contact noise and contact resistance, and in addition, tends to pit and wear more rapidly.

It further will be appreciated that high contact pressures are necessary in mechanical switches in order to maintain low contact resistance under circumstances of severe environmental stress. This high contact pressure is required to penetrate undesirable corrosive products that are deposited on the switch contacts. As known to those skilled in the art, such high contact pressures are not desirable because of concomitant requirements for high actuation energy, and high actuation electric power consumption, as in the case of electromagnetic relays. Manifestly, high electric power consumption is undesirable in applications such as. satellites in which the total available electric power is limited.

Accordingly, it is a general object of this invention to provide a new and improved switch construction which successfully overcomes the above-enumerated deficiencies of prior art mechanical switches.

It is another object of this invention to provide a unique fluid switch constructionformed of a viscoelastic, deformable tube partially filled with an electrically conductive, non-wetting fluid which is in contact with only portions of the internal peripheral surface thereof, said fluid also being in contact with two or more terminals extending through said tube to thereby provide an electrical path therebetween, the internal peripheral surface of said tube being defined by two or more arcuate portions contiguous with each other such that a sharply discontinuous electrical circuit resistance or switching function can be effected between the terminals as a result of the deformation of said tube for an amount less than the deformation required to cause the internal opposing peripheral surfaces of the tube to abut each other.

It is still another object of this invention to provide a novel fluid switch construction, as above, which eliminates mechanical contact bounce or oscillation.

It is a further object of this invention to provide an improved sealed, long life fiuid switch construction which is relatively immune to the deteriorating eflfects'of contamination from dust particles or from the presence of organic and inorganic corrosive vapors.

It is a still further object of this invention to provide a new and improved fluid switch construction which incorporates a viscous damping action that serves to suppress contact bounce during periods of relatively high environmental acceleration.

It is another object of this invention to provide a novel fluid switch construction which is characterized by the combination of low contact pressure and a high degree of make-break reliability, thereby requiring only low electric and mechanical power consumption.

It is still another object of this invention to provide a new fluid switch construction, as above, which avoids the prior art problem of mechanical abrasion and wear between switch contacts, and additionally avoids the prior art problem of the generation of spurious noise due to the sliding action of one switch contact upon another.

It is a further object of this invention to provide an improved fluid switch construction which can easily be shaped and sized as desired so as to properly fit within the housing of the electrical apparatus with which the switch is used, and which also is adapted to be fitted within a hermetically sealed container to provide a new and useful hermetically sealed switch.

It is a still further object of this invention to provide a unique fluid switch construction which has a high degree of internal damping and is shockproof, such that it may be dropped or subjected to severe shock without damage.

It is another object of this invention to provide a new and improved fluid switch having a non-wettable electrically conductive fluid for completing an electrical circuit between the switch terminals which is not position sensitive and therefore, may be oriented as desired, and which is adaptable for use with a multiplicity of terminals without undue cost or circuit complication.

The novel features which are characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following description taken in conjunction with the accompanying drawing in which:

FIGURE 1 is a chart illustrating the resistance versus force characteristics of a novel fluid switch embodying the principles of the present invention;

FIGURES 2, 3, 4 and 5 are transverse cross-sectional views of a fluid switch constructed in accordance with the present invention and progressively illustrating the sharply discontinuous switch action as a result of the deformation of the fluid containing tube;

FIGURE 6 is a view, partially broken away and in cross-section of a single pole, double throw switch embodying the invention and in an open switch-closed switch condition;

FIGURE 7 is another view of the single pole, double throw switch of FIGURE 6 in its closed switch-closed switch condition;

FIGURE 8 is another view of the single pole, double throw switch of FIGURE 6, partially broken and in cross-section, in a closed switch-open switch condition;

FIGURE 9 is a detailed cross-section view of one sharply discontinuous manner.

switching function- V FIGURE 12 is another perspective view of the fluid switch construction of FIGURE 11 shown in a closed switch condition;

FIGURE-13 is a cross-sectional view of the fluid switch construction taken substantially as shown along line 1313 of FIGURE 12;"

FIGURES 14 and 15 illustrate still another embodi-' ment of a single pole, double throw switch asparticularly adapted to relay or panel switch applications and shown in its closed switch-closed switch, and its closed switchopen switch conditions, respectively;

FIGURE '16 is'a plan view of still another illustrative embodiment of the fluid switch comprising the present invention;

FIGURES 17, 18 and 19 are views, partly in crosssection, of the illustrative embodiment of FIGURE 16, taken along lines'17-17, 18'18 and 19-19, respectively; and

FIGURE 20 is a perspective view of still another illustrative embodiment of the invention wherein the novel fluid'switch is embodied in a hermetically sealed housing for use under conditions of severe environmental stress.

The novel fluid switch construction of the present invention is described hereinbelow and illustrated in the drawings in the form of several'illustrative and practical embodiments, but those skilled in the art will appreciate that the present invention may be incorporated in numerous other practical embodiments and applications, such as toggle switches, electromagnetic relays, low level signal sampling switches, and-the like, and that the.

presently illustrated embodiments are not intended to limit the scope of the invention in any way whatsoever.

Referring now to the drawing, and more particular to FIGURE. -1 thereof, there is shown a chart illustrating the sharply'discontinuous nature of the resistance versus force characteristic of a novel fluid switch embodying the present invention. As explained in greater detail hereinbelow, the invention comprises a deformable tube partially filled with an electricaly conductive, non-wetting fluid establishing an electrical path between the terminals extending through the tube. In accordance with'a feature of this invention, the application of force to deform the tube at points between the terminals results in a sudden rupturezof' the fluid to provide a high resistance, open circuit. In accordance with another feature, the required force and deformation are less than that required to cause the internal opposing peripheral surfaces of the tube to abut each other. i

'As a result 'ofthe novel structure of this invention, this electrical circuit switching function is attained in a FIGURE 1 is a curve of the resistance versus force characteristics of] one emobdiment of the inventio'mwhcrein the values of R/Ro represent resistance ratio betwene the fluid switch terminals with indicated deformation'force over the resistance with the zero deformation force. -As there shown,-

the resistance changes abruptly to an extremely'high,

open-circuit, resistance value to provide a highly desirable Those skilled in the art will appreciate that it is known to utilize, a deformable tube completely filled with a conductive fluid to provide a continuous variable resistance function as the tube is deformed. 7 Such a variable resistance device is shown for example, in the patent to Kocmich, No. 2,518,906,, which is directed'at obtaining a continuous. variable resistance versus force characteristic of the type required for potentiometers, linear mechanical-to-electrical transducers, and the like. In contrast to the continuous resistance devices exemplified by Kocinich, the present invention, due to its novel principles of operation which are based .uponthe interaction between surface tension forces and internal pressure forces, causes a sharply discontinuous self-regenerative switching action. This is eifected by the novel configuration and thepartialfilling of, a deformable tube with a non-wetting" electrically conductive fluid, which provide the desired positive electrical switching characteristics in response to tube deformation.

By reference to FIGURES 2,3, 4 and 5 of the drawing, the principles of operation of the invention may clearly be understood. As there shown, the .invention primarily comprises ;a hollow envelope or tube It advantageously formed of a visco-elastic deformable material which preferably, is chemically inert. Ithas been found desirable in the construction of the hollowtube 1 9 to utilize elastomer materials, such as silicone rubber, and other similar deformable materials. As explained in reater detail hereinbelow, the viscoelasticdeformable material comprising the hollow tube :10 is closed at its ends so as to be hermetically sealed for enclosing an electrically conductive, non-wetting fluid 12 therewithin. Advantageously, as explainedin greater detail hereinbelow, the tube 10 is partially filled with the nonwetting electrically conductive fluid 12, with the remaining volume of tube ltibeing filled with a non-conductive fluid, as illustrated by the reference numeralflS shown in FIGURES 2 through 5. In actual practice, it has been found desirable to form the fluid 12 of mercurly, or any other electrically conductive fluid which does not wet the internal peripheral surface of the tube'lt);

' In the practical application of the novel fluid switch as explained in detail hereinbelow, a plurality of spacedapart electrical terminals (not shown in FIGURES 2 through 5) are positioned through'the viscoelastic deformable. material of the hollow tube 19 soas to be in contact with the conductive fluid ,12 within the tube envelope. While two terminals may be used to provide 1 a single, pole, single throw switch, it is a feature of the present invention that any number of terminals can be used 7 in the switch, to provide the number of poles required for a desired switching function. v I V In a two terminal, single pole, single throw switch, a

low resistance electrical path is'present between the spacedapart electrical terminals untilsuch tim'eas the envelope of the deformable tube 10 is deformed by a suitable switch arm 18 for an amount suflicient to abruptly rupture the electrical-path provided by the conductive fluid tube 12 between the terminals. This action is illustrated by FIG- URES 2 through 5 which show this sharply, discontinuous switching action 'as a result of. the progressive deformation of tube 10. I

Itecan be seen that as'the switch arm 1S presses down on the flexible tube 10, the latter is deformed and its cross-sectionalarea is reduced at the point of deformation. When the cross-section of thedefor'mable tube 10 has been reduced to a certain dimension, the forces of surface tension and cohesion overcome the forces tending to'holdjthe conductive fluid 12 togethensuch latter forces being comprisedof the internal tube pressure and the adhesive forces between the conductive fluid 12 and the internal peripheral surface of the tube '10. At this time, and it will be noted that it occurs before the opposing internal peripheral surfaces of the tube 10 are caused to abut each other to physically close the'tube,.the conductive fluid column abruptly ruptures to cause the electrical resistance of thetube to rise to a very high-value equivalent to an open switchcondition between the terminals.

otherwise-and that the shape which the non-wetting conductive fluid 12 takes within the tube It) depends on the shape of the tube envelope, on the adhesion between the conductive fluid I2 and the walls 20 and 22 of the tube, on the pressure within the conductive fluid 12, and on the surface tension of the conductive fluid 12. The high interfacial tension between the fluid and internal walls or non-wetting property of the conducting fluid causes the fluid to conform to the internal peripheral shape of the tube except at those points Where the forces due to surface tension pull the conductive fluid 12 away from the walls 20 and 22 of the tube. Wherever the fluid surface forms a radius r, surface tension forces try to enlarge this radius, with the size of the radius being inversely proportional to the effect of the surface tension forces. Thus, the smaller the radius of the fluid surface, the larger will be the force tending to enlarge the radius. At any point where the fluid surface is not in contact with the walls of the container, the radius will be such that the surface tension force exactly balances the force due to pressure within the fluid. At any point where the fluid surface leaves the internal walls of the tube envelope, the angle a which the fluid surface makes with the internal wall depends on the adhesion of the fluid to the container walls and on the surface tension forces.

FIGURE 2 of the drawing illustrates a cross-sectional view of a deformable tube envelope 10 comprised of the opposing Walls 20 and 22 and having a non-Wetting, electrically conductive fluid 12, such as mercury, provided therewithin. It will be noted that at the edges of the tube envelope 10, that is, at the junctions of the tube walls 20 and 22, the fluid surface does not conform to the shape of the tube Walls, but rather takes on a certain radius r, and makes the certain angle at with the tube envelope walls, which angle a is dependent upon such factors as fluid internal pressure, adhesion and surface tension. At all other points within the tube envelope 10, the non-wetting electrically conductive fluid l2 conforms to the shape of the internal peripheral surface of the tube walls 20 and 22. In FIGURE 2, the tube envelope 1% is shown as positioned between a fixed base member 24 and a movable switch arm 18. Advantageously, base member 24 may be planar as shown, or it may be raised or shaped as desired to facilitate the switch action of switch arm 18.

As illustrated in FIGURES 3, 4, and 5, the movable switch arm 18 is'progressively depressed further and further against the tube envelope 14 in a direction towards the fixed base member 24. If, as in the simplest case, it is assumed that the fluid internal pressure and adhesion is the same in each case, the radius of the electrically conductive non-wetting fluid surface and the angle at which it makes with the tube envelope walls will be the same in all cases (illustratively shown as 60 in FIGURES 2, 3, and 4). The net effect of altering the shape of the tube envelope 16 at the point of depression by the movable switch member 18 is to cause the electrically conductive fluid boundary to move inwardly towards the center of the tube from the outer edges as defined by the junction of the tube walls 20 and 22. This movement results since it is the only way that the angle of fluid contact 06 and the fluid radius r can be maintained, as shown above.

As shown in FIGURE3, the fluid boundary has moved inwardly from the original boundary shown in FIGURE 2 as a result of the deformation of the envelope provided by the depressed movable switch arm 18. If, as shown in FIGURE 4, themovable switch arm 18 is depressed still further, the fluid boundary will move even closer towards the'center of the tube envelope, and at a certain degree of deformation of the tube envelope, as illustrated in FIG- URES of the drawing, the spacing in the center of the tube envelope will reach a point Where it will be physically impossible for the fluid radius r to be maintained. At this point, the fluid geometry becomes unstable and abruptly ruptures to create a low pressure volume at the point of separation. Those skilled in the art now will appreciate that this rapid action creates a positive make-break switch characteristic that occurs very rapidly. Thus, there will be a sharp discontinuity in the electrical resistance on the electrical conductive path between the terminals 14 and 16 to provide a highly desirable switching action.

It further will be appreciated by those skilled in the art that due to the considerations discussed hereinabove, this abrupt and positive on-off switching action has taken place with a deformation of the tube envelope less than the deformation which would be required to cause the internal peripheral surfaces of the tube walls 20 and 22 to contact or abut each other. Thus, it is not necessaryin accordance with the novel principles of the present invention to cause the tube walls 20 and 22 to be placed into physical contact with each other to provide the desirable switching action since the particular geometry of the internal peripheral surface of the tube and the combined characteristics of the tube together with the non-wetting electrically conductive fluid serve to provide a sharply discontinuous switching action in a highly desirable manner which completely eliminates the prior art problems or effects of contact oscillations or bounce.

It further will be appreciated by those skilled in the art that the dynamic stress in the deformable material forming the tube envelope 10 should be held to a minimum in order to reduce the degree to which the deformable tube envelope will take a permanent set. Accordingly, it is a feature of this invention that in order to achieve such low dynamic stresses, and to cause the fluid column to break abruptly and in a uniform manner after repeated depressions, it has been found particularly desirable to form the tube envelope It} with a crosssectional configuration Such as that shown in FIGURES 2 through 5 wherein the tube has an internal peripheral surface defined by at least two arcuate sections contiguous with each other and meeting at a junction forming a geometric surface discontinuity. However, if desired, other crosssectional configurations may be utilized to achieve the desired compromise between low dynamic stress of the tube envelope and high reliability of the abrupt breaking action of the fluid column.

One highly desirable advantage which accrues from the use of the present invention resides in the low force which is required to maintain the reliable on-olf switching action of the fluid column within the tube envelope. For example, in one highly successful embodiment of the present invention, it was found that a typical value of fluid breaking force equaled only .35 ounce of switch arm deformation pressure against the deformable tube envelope, which relatively low force resulted from the highly desirable feature that the internal opposing wall surfaces of the tube envelope did not have to be placed into abutting contact with each other.

It. also will be appreciated by those skilled in the art that when the fluid column 12 within the tube envelope abruptly ruptures in response to the deformation of the tube walls, a illustrated in FIGURES 2 through 5 of the drawing, a partial vacuum or volume of very low internal pressure is created within the tube envelope between the ruptured portions of the fluid column which is of considerable advantage in suppressing the deterioration eifect caused by electrical arcing normally present in the switch breaking operation of an electrical circuit. It also can be seen that this partial vacuum or volume of very low internal pressure serves to enhance the action of the movable switch arm which is deforming the tube envelope by reducing resistance to its movement. Since the tube envelope 10 may be formed in any desirable shape or size, and since it easily may be hermetically sealed, the conductive fluid 12 Within the envelope is protected from the deteriorating effects of contaminants such as dust particles or corrosive vapors.

In accordance with a further feature of the present fluid switch invention, certain materials such as titanium oxide or tin oxide may be deposited on the internal peripheralsurfa-ce of the tube 10. This serves to improve a and enhance the maintenance of a high interfacial tension or non-wetting property between the conductive fluid and the internal peripheral surface of the tube.

In a practical embodiment of the present invention, themevableswitoh arm 18 may be coupled toa suitable mechanical actuator such as a leaf spring forming a part of .a mechanical or electromagnetic switch structure. Under these circumstances, it will be appreciated that the viscous damping action provided by the movement of the conductive fluid 12 in the deformable tube envelope lil will be mechanically coupled to the movable switch arm and therefrom to the actuating mechanism. Manifestly, this coupling of the viscous damping action tends to reduce any tendency of arnechanicalsystem coupled to the fluid switch to oscillate or bounce and thereby cause erroneous signals to be created; It further can be seen that if the movable switch arm 18 is subjected to a sudden high acceleration, such as might be present under-the environmental conditions associated with high speed devices such as space vehicles, the viscous damping effect provided by the displacement of the conductive fluid 12 withinthe tube envelope Will serve to materially reduce the tendency forthe fluid to come together and cause false contact, in sharp contrast to the operation of a conventional metallic contact switch structure.

The principles described hereina'bove with respect to FIGURES 1 through 5 may be utilized in a single pole, double throw switch ,by incorporating three terminals within the .tube envelope and by using two pivotally inounted'switch arms for deformingthe tube envelope.

Thus, as illustrated in FIGURES 6, 7, and 8 of the drawing, the tube envelope 10 is partially filled with the electrically conductive fluid 12 and is hermetically sealed, as

by the end caps 26 .and 28. Electric terminals are positioned through the tube envelope at each end thereof and are electrically connected to the conductor 30 and 32* In addition, a third electric terminal is respectively. positioned through the tube envelope at a point intermediate its length, and is connected to the conductor 34. 1

As particularly illustrated in FIGURE 6 of the drawing, the movable switch arm comprises the oppositely disposed switch operators 36 and 38 pivo-tally mounted by the cross arm 40 on the fulcrum 42. When the switch arm operator 36 is pivoted downwardly for depressing the tube envelope 10, the deformation of the tube wall 22 described hereinabove, for opening the circuit between the electrical conductors 39 and 34, At this time, the elec-.

trical circuit between conductors 34 and 32 is closed.

As shown in FIGURE 7 .of the drawing, when the 'switch arm is in the neutral position with the switch provided mechanically by a suitable adjusting post or clampmeans, as desired. j s l Another alternative embodiment ofthe pre'sentinvention incorporating the above described principles is shown in FIGURES 9 and 10 of the drawing, which illustrate a bounceless miniature switch construction. As there shown, the fluid switch construction comprises a switch housing formed of a suitable insulating material, such as plastic or the like, comprised of a switch cover portion 36 and a switchbody portion 48. The switch body portion 43 is formed with the-laterally extending post which advantageously comprises an arcuate outer peripheral surface around which the sealed hollow tube 10 of viscoelastic, deformable material is positioned. .The switch support members 52and 54 are provided on'opposite sides of thedeformable tube It? and the fixedpost 50, and are spaced from the deformable tube 10 a. sufficient distance such that the tube is not deformed to provide an electrical circuit switching function except as a result of the operation of a movable switch arm 56 in the manner described hereinbelow.

Advantageously, the movable switch arm 56 is secured to a pivotable leaf spring 58 which is pivoted at its remote end to a fixed terminal post 60, securely attached. to the switch body portion 48 of the switch housing. Advantageously, in this'illustrative embodiment. of the; invention, a hoop-like over-center: spring, 62. is secured at one the leaf spring operator 70 and the'lower' portion of the causes the fluid 12 to abruptly rupture, in themanner.

ductors 30 and 34 and also betweenthe conductors 34 and 32. However, as shown in FIGURE 8 of thedraw ing, whenthe pivoted switch arm is operated to depress the switch operator 38 for defonming the wall 22 ,at the opposite portion of the tube envelope It the conductive fiuid 12 therewithin ruptures at the point of deformation to open the, electrical circuit between the' conductors-34 and 32. At thistime, the electrical circuit between the conductor 30 and 34 remains: closed, thereby providing a highly desirable single pole-double throw switch action.v

, viscous damping which serves to facilitate the switching action. If desired, this additional viscous damping may push-button 68. Thus, it will be appreciated by those skilledin the art that the leaf. spring 58 will be maintained in the position shown in FIGURES 9 and 10 until such time as the manually operable pushbutton 68 is depressed against the force of the. return spring 72 to cause the leaf spring operator 70 to pivot the leaf spring 58-downwardly from the position shown in FIGURES 9 and 10. Uponrelease of the-manually operable push button 68,,the return spring 72 causes thepush-button 68 to return to its initial position, at which timethe leaf spring 58 also is'pivoted. upwardly to return to its initial position. It will berecognized that the pivoting action of leaf spring 58 is facilitated and enhanced by the operation of. the over-center spring 62 which provides asnap action to the leaf spring pivoting operatiom As further shown in the illustrative embodiment of FIGURES 9 and 10, the sealed deformable tube 10 may be provided with the'terminal conductors 3i) and 32 at I itsrespective ends and the. terminal conductor'34 at an intermediate position, such terminal conductors being extended into the interior portion of the deformable tube selectively be increased or decreased by adjusting the,

cross-sectional configuration of the neck 44 .(shown in dotted lines) of the tube envelope 10. Thismay be for contact with the non-wettable fluid therein in the manner described hereinabove. The terminal conductor so is connected to the'te'rminal post 74,.the terminal con-' ductor 32is connected to the terminal post 7,6, and the terminal conductor 34 is connected, through the leaf spring 58, tothe terminal post 69, with all of such terminal posts being accessible fromthe exterior of'the switch housing to permit the switch to .be suitably connected in 'an electrical circuit in any desired manner.

The operation of the bounceless miniature-fluid switch of FIGURES 9 and 10 willnow be described Normally, the movable switch arm 56 will be pivoted in engagement with the upper portionof the deformable tube It), as illustrated in FIGURES 9 and- 10, due to the action of :the ,pivotable leaf spring SSJand'theoVer-center spring 75 62. Under these circumstances, the fluid within the der v 9 formable tube 10 at the point of deformation is caused to rupture to open the electrical circuit path between the terminal conductors 30 and 34. At the-same time, a closed electrical circuit path is present between the termi-. nal conductors 32 and 34.

When the manually operable push-button 68 is depressed against the bias of return spring 72, the leaf spring operator 70 moves the pivotable leaf spring 58 downwardly carrying the movable switch arm 56 and the over-center spring 62 with it. When the junction of the leaf spring 58 and over-center spring 62, identified at 80, moves downwardly below the center point of the overcenter spring 62, the net force on the leaf spring 58 and switch arm 56 is downward with the result that the switch arm '6 snaps into position to deform the lower section of the partially filled, deformable fluid containing tube 10.

In accordance with the above-described operation of the deformable tube 10, this causes the electrical circuit path in the lower tube portion to abruptly rupture so as to open the electrical circuit path between the terminal conductors 32 and 34. Also, at this time, the upper portion of the deformable tube will return to its normal, undeformed condition to provide a closed circuit path between the terminal conductors 30 and 34. This return action is provided by the elastic restoring properties of the viscoelastic material forming the tube 10 and by the natural attraction which the non-wettable conducting fluid, such as mercury, has for itself when the deformation of the tube is removed.

It further will be appreciated that the post 50 around which the deformable tube 10 is supported may selectively be adjusted to increase or decrease the cross-sectional area at the neck of the tube 16 such that the additional viscous damping provided by the movement of the nonwetting fluid back and forth through the tube may be selectively increased or decreased, as desired. The selective adjustability of the post 50 is illustrated by the arrows 51 shown in FIGURE 10.

Still another alternative embodiment of the invention incorporating the above-described principles is shown ,in. FIGURES 11, 12 and 13 of the drawing, which illustrate a fluid switch having a pivotable operation of the deformable, fluid containing tube for effecting the switching function. As there shown, the viscoelastic deformable tube 10 is partially filled with a non-wetting, electrically-conductive fluid as hereinabove discussed. However, in this embodiment, the movable switch arm which heretofore has been described as deforming the tube to effect a switching function has been eliminated. In lieu of the use of such a switch arm, the deformable tube 10 is formed in a V-shape having an acute angle e, defined between the arms of the V-shaped tube. One end of the tube 10 is attached to a fixed member 82, while the other end of the deformable tube 10 is attached to a hinged, or pivotable, member 84. Advantageously, the members 82 and 84 may be suitable clamps or any other holding devices suitable for receiving and securely supporting the ends of the deformable tube 10 therewithin. Also, it will be appreciated by those skilled in the art, that the hinged or pivotable support member 84 may, in some applications, be a pivotable leaf spring, relay armature, or other member responsive to a mechanical or electromagnetic actuation.

. 'In the operation of theembodim'ent shown in FIG- URES 11, 12 and 13, the movement of the hinged or pivotable support member 84 causes the acute angle between the arms of the V-shaped deformable tube It) to be reduced by a small amount to define the angle as shown in FIGURE 12. This will cause the apex 88 between the arms of the V-shaped deformable tube 10-to be reduced in thickness to the point where the fluid surface tension becomes predominant over the forces tending to hold the fluid together, and the fluid abruptly ruptures at the apex 88 in response tothe pivoting action. This is particularly illustrated in FIGURE 13, which shows the cross-sectional area of the tube at the apex 88 will be restored to its initial condition and the circuit path will be abruptly closed, thereby completing an electrical circuit between the conductors 30 and 32.

Still another illustrative embodiment of the present invention incorporating the above-described principles is shown in FIGURES 14 and 15 of the drawing which illustrates the invention as particularly applied to a relay or panel switch. As there shown, the switch takes the form of a single pole, double throw switch comprising a support member 90 having a plurality of leaf springs extending therefrom. Leaf springs 92 and 94 extend for a smaller distance than the center leaf spring 96, which may be terminated by a suitable opening finger 98. A pair of deformable tubes partially filled with electrically conductive fluid, similar to the tube 10 heretofore described, is used in this embodiment with the first deformable tube being generally V-shaped and positioned around the leaf spring 92, and with the second deformable tube 102 being generally V-shaped and positioned around the leaf spring 94. The elongated center leaf spring 96 extends between the one arm. of each of the V-shaped tubes 1% and 102, as illustrated in the drawing.

FIGURE 14 illustrates this embodiment of the invention in the normal, or unactuated, condition wherein an electrical path is completed through each of the deformable tubes 100 and 102 such that a closed electrical circuit exists between the terminals 30 and 34, and between the terminals 32 and 34. When a force F is applied to the operating finger 98 of the center leaf spring 96, as illustrated in FIGURE 15, it causes the center leaf spring 96 to bend downwardly to compress the deformable tube 102 and to reduce the thickness at its apex at the center of the deformable tube. In a manner described heretofore, this causes the electrically conductive fluid within tube 102 to abruptly rupture and thereby break the electrical circuit path between the terminals 32 and 34. At this time, the electrical circuit path in the deformable tube 100 will remain closed. However, it will be appreciated that if the force F is exerted against the center leaf spring 96 in the opposite direction, it will cause the reverse operation to take place, wherein the tube 100 is deformed at its apex to open its electrical circuit path between conductors 3t) and 34 and wherein the electrical circuit path in tube 102 will be restored upon removal of the tube deforming force F. An advantage in the use of a V-shaped tube resides in the fact that such tubes require even less actuation force due to the lever action inherent in their operation.

Those skilled in the art will readily appreciate that deforming force F may be generated manually through a panel button, or if desired, electromagnetically as by nreans of a magnetic armature and coil assembly. Those skilled in the art will further appreciate that the invention is not restricted to the use of two or three terminals, as illustratedtin the illustrative embodiments described herein, but rather that the invention may incorporate any number of contacts, leaf springs, and deformable tubes, such as might be incorporated in a multi-channel sampling switch, for example. One of the features of the present invention is that the addition of such terminals can be effected without unduly complicating the switch construction, operation, or cost.

. Still another illustrative embodiment of the present invention is shown in FIGURES 16 through 19 of the drawing. Advantageously, this form of the inventive fluid switch comprises a deformable tube 10, partially filled 1 1 with a non-wetting conductive fluid, as described above, and having three spaced conductors 30,v 34, and 36 positioned therethrough into contact with the fluid within the tube.

In acordanee with a feature of this embodiment, a pair of U-shaped spring arms 100 and 112 of resilient material are positioned upon the deformable tube-1i) so as to normally provide an open circuit between conductors 30 and 36,. and between conductors 36 and 34, respectively. Towards this end, the deformable tube is positioned on {the base plate 196 of an L-shaped support member 104 having an upstanding flange 106. One end of each of the U-shaped spring arms 110 and 112 is securely fastened to an edge portion of the support member 1114 as shown in FIGURES 16 and 17 such that the resilient action of thespring arms causes their remaining free ends to be biased downwardly against the tube 16 for northe basic partially-filled, deformable, fluid containing tube It? is positioned within a gas-tight metal container 130.

Container 130 advantageously is formed with the base latter may be a buckled plate or corrugated diaphragm mally deforming the latter. to provide the circuit opening a switch function described above.

Advantageously, a cam member 118 is adjustably mounted to selectively raise or lower the free ends of spring arms 110 and 112 for effecting circuit opening and 7 closing switch functions. In accordance with a feature of this invention, this desirable result is achieved by means of a manually actuatable slide knob 120 which is coupled to the cam ,member 118 by means of a linking arm 116 slidably positioned through the slot 114 in the flange 108 7 of support member 1114. Asparticul arly shown in FIG- URES 16 and 17 the cam member 118 is formed with two oppositely. inclined upper cam surfaces 122 and 126 separated by a flat cam surface 124 generally parallel to the V base-plate 106 of support member 104.

a g If, in the operation of the invention, the slide knob 120 is moved to the position shown in FIGURES 16 and 17, the flat cam surface 124 of cam member 118 causes the free end of the U-shaped spring arm 112 to be raised to thereby release the deformable tube 10. This is illustrated in FIGURE 19 of the drawing, and, as described hereinabove,'causes a closed electrical circuit path to be provided between conductors 34 and 36. At this time, however, the inclined cam surface 122 will be positioned below the free end of U-shaped spring arm 11%). Due to I the slope of the inclined cam surface 122, the free end of spring arm 110 will not be raised but rather will be in deforming engagement with the tube 110. This is illustrated in FIGURE 18 and causes an open electrical circuit to exist between conductors 30 and 36.

, Those skilled in the art will now appreciate that the slidable knob 129 may be moved to a central locationin the slot 114 to cause the free ends of both spring arms to be raised by the inclined cam surfaces 122 and 126 to closeithe circuit paths between conductors 30 and 36, and between conductors 36 and 34. Alternatively, the slide knob 12i) may be moved to its other extremity in slot 114 to cause the free end of spring arm 11!) to be raised by .cam surface 124 and tocause the free end of spring arm 126 to be positioned into deforming contacts with the 1 shown in FIGURES 16 through 19 of the drawing.,Due

to its reliable and compact characteristics, this switch embodiment is readily adaptable to miniaturized electrical 1 devices, such as hearing aids, transistor radios, and the Astill further embodiment of the. invention is illuswhich advantageously can beultrasonically Welded to the flange 136 to provide the desired'gas-tight seal. Also, glass seals 142' may beprovided in the wall 132 of the container 1341 for enabling the conductors 30 and 32m be suitably connected to the deformable tubep10. f

In the use of the inventive embodiment of FIGURE 20, aswitch arm member 140,'of'suitably rigid material, is mounted within the container between the'deformable tube 10 and the diaphragm 138. Preferably, the switch arm member, 140 is secured to thediaphragm 138'such' that the raising of the latter removes the member 14$ from, a circuit opening deforming engagement with tube 10 and the lowering of diaphragm 138 places the member that the switch of the present invention is relatively shockproof due to its high internal damping and therefore, can be dropped or subjected to shock without probability of switch damage. 1

While there has been shown and described a specific embodiment of the present invention, it will, of course, be understood that various modifications and alternative constructions may be made without departing from the true spirit and scope of the invention. Therefore, it is intended by the appended claims to cover all such modifications and alternative constructions as fallwithintheir true spirit and scope.

What is claimed as the invention isz.

1. The improvement .of afluid switch construction comprising the combination of a sealed, hollow'container formed of a viscoelastic, deformable material, a plurality of electrical terminals spaced from each other and extending through said container into its interior hollow portion, an electrically conductive, non-wetting fluid par-v tially filling the interior hollowportion of said container and in contact with only portions of theperipheral surface thereof, said fluid being in contact with said electrical terminals so as to provide a low resistance electrical circuit, the internal periphery ofsaid container being de-.

fined bya plurality of arcuate surfaces contiguous with each other and meeting at junctions forming regions of surface discontinuity such that a sharply discontinuous velectrical circuit switching function can be efiected betrated in FIGURE 20 of the drawing. There are many applications in which an electrical switch must operate under very severe environmental stress, such as in an en vironment of concentrated sulfuric or nitric acid, or surrounded by cetain rocket or jet fuels. Under suchadverse conditions, hermetic sealing of the switch often is required. V

In accordance with a feature of the present invention,

tween the terminals as a result of the deformation of said containerfor an amount less than the deformation-required to cause the internal opposing peripheral surfaces of the container to completely abut each other. v

2. The improvement of a fluid switch construction comprising the combination .of a sealed, hollow container formed of a viscoelastic, deformable material, a plurality of electrical terminals spaced from each other and extending through saidc-ontainer'into its interior hollow por-' tion, an electrically conductive, non-wetting fluid partially filling the interiorhol'low portion of said container and in contact with only portions of the inner peripheral surface thereof, the smallest radius of the inner peripheral surface of said container being less than the radius of the conductive fluid therewithin such that a cross-section of said partially filled container comprises three separate phases, namely, a non-wetting electrically conductive fluid phase, a relatively non-conductive fluid phase defining the interspace between the non-wetting electrically conductive fluid and the inner peripheral surface of the container, and a solid phase comprised of the inner surface of said container, said fluid being in contact with said electrical terminals so as to provide a low resistance electrical circuit path between said terminals when the container is'not deformed, and means adapted to engage the outer surface of said container for deforming the container to cause the low resistance electrical path between the terminals to be abruptlyruptued to form a sharply discontinuous electrical circuit switching function that results in a high resistance open circuit between the terminals.

3. The improvement of a fluid switch construction comprising the combination of a sealed, hollow container formed of a viscoelastic, deformable material, a plurality of electrical terminals spaced from each other and extending through said container into its interior hollow portion, an electrically conductive, non-wetting fluid partially filling the interior hollow portion of said container and in contact with said electrical terminals so as to provide a closed electrical path between said terminals when the container is not deformed, and switch arm means engaging the outer surface of said container for deforming the tube by an amount less than that required to place the internal opposing faces of the container in complete abutment to cause said fluid to be ruptured and the closed electrical path between the terminals to be opened, said switch arm means being pivotally mounted for pivotal movement between two spaced-apart points on the outer surface of said container, whereby the deformation of said container by said switch arm means at one of said points causes the electrical path between one pair of said terminals to be abruptly opened and the deformation of said container at the other point causes the electrical path between another pair of said terminals to be abruptly opened.

4. The improvement of a fluid switch construction in accordance with claim 3 further comprising a post member positioned adjacent the neck of said sealed, hollow container and selectively movable relative thereto to adjust the cross-sectional thickness of said container for selectively increasing or decreasing the viscous damping provided by the movement of the fluid within the container.

5. The improvement of a fluid switch construction co prising the combination of a sealed, hollow container formed of a viscoelastic, deformable material, said container being generally V-shaped and having a pair of arm portions extending from an apex portion to define an acute angle therebetween, a plurality of electrical terminals spaced from each other and extending through said container into its interior hollow portion, an electrically conductive, non-wetting fluid partially filling the interior hollow portion of said container and in contact with said electrical terminals so as to provide a closed electrical path between said terminals, and a pair of support members secured to spaced-apart points on said portions of said V-shaped container, said support members being movable relative to each other to increase or decrease the size of the acute angle between said arm portions, the decrease of said acute angle between said arm portions serving to effect a sharply discontinuous electrical circuit prising the combination of a plurality of scaled, hollow containers, each formed of a viscoelastic, deformable material; each of said containers comprising a plurality of electrical terminals spaced from each other and extending through the container into its interior hollow portion, and an electrically conductive, non-wetting fluid partially filling the interior hollow portion of the container and in contact with said electrical terminals so as to provide a closed electrical path between said terminals; movable switch arm means positioned between a pair of said containers .and adapted to be selectively moved against the outer surface of either container for deforming the latter to cause the closed electrical path between its terminals to be opened, such a sharply discontinuous electrical circuit switching function can be effected between the terminals of the deformed container as a result of its deformation for an amount less than the deformation required to cause the internal opposing peripheral surfaces of the container to completely abut each other.

7. The improvement of a fluid switch construction comprising the combination of a plurality of V-shaped sealed, hollow tubes, each formed of a viscoelastic, deformable material and including a plurality of electrical terminals spaced from each other and extending through said tube into its interior hollow portion, and an electrically conductive, non-wetting fluid partially filling the interior hollow portion of said tube and in contact with said electrical terminals so as to provide a closed electrical path between said terminals; and movable switch actuation means positioned between a pair of said tubes and adapted to selectively be moved against the adjacent arm of each V-sh-aped tube for selectively deforming the engaged tube to cause the included angles between the V-shaped arms of the tube to be reduced, such that a sharply discontinuous electrical circuit switching function can be effected between the terminals of the deformed tube as a result of the deformation of said tube for an amount less than the deformation required to cause the internal opposing peripheral surfaces at the apex of the V-shaped arms of the tube to completely abut each other.

8. The improvement of a fluid switch construction comprising the combinationof a sealed, hollow tube formed of a viscoelastic, deformable material, a plurality of electrical terminals spaced from each other and extending through said tube into its interior hollow portion, an electrically conductive non-wetting fluid partially fllling the interior hollow portion of said tube and in contact with only portions of the peripheral surface thereof, said fluid also being in contact with said electrical terminals so as to provide a closed electrical circuit path between said terminals when the tube is not deformed, and means engaging the outer surface of said tube for deforming the tube to cause the closed electrical path between the terminals to be abruptly opened such that a sharply discontinuous electrioal circuit switching function is effected between the terminals as .a result of the deformation of said tube for an amount less than the deformation required to cause the internal opposing peripheral surfaces of the tube to completely abut each other.

9. The improvement of a fluid switch construction comprising the combination of a sealed, hollow container formed of a viscoelastic, deformable material, a plurality of electrical terminals spaced from each other and extending through said container into its interior hollow portion, an electrically conductive non-Wetting fluid partially filling the interior hollow port-ion of said container and in contact with only portions of the inner peripheral surface thereof, the smallest radius of said inner peripheral surface of said container being less than the radius of the conductive fluid therewithin such that the conductive fluid is spaced from the inner surface of the container at some portion thereof, said fluid also being in contact with said electrical terminals so as to provide a closed electrical cir cuit path between said terminals when the tube is not deformed, a resilient member biased into deforming engagement with said container, and multiposi-tion cam means adapted in one position to permit the resilient member to engage the outer surface of said container for deforming the container to cause the closed electrical path between the terminals to be abruptly opened, and furtheradapted in a second position toraise the resilient member from the container to cause the opened electrical path between the terminals to be abruptly closed, such that a sharply discontinuous electrical circuit switching function is cf.- fected' between the terminals by actuation of said cam means. I

10. The improvement of a fluidfswitch construction comprising .the combination of a sealed, hollow tube formed of a visooelastic, deformable material, a plurality of electrical terminals spaced from each other and exthereof, said internal peripheral surface being coated with material to provide a higher interfacial tension between the tube and 'thefluid, said fluid also being in contact with said electrical terminals so as to provide a closed electrical circuit path between said terminals when the tube is not deformed, and means adapted to engage the outer surface of said tube for deforming the tube to cause the closed electrical path between the terminals to be abruptly opened suchtha't a sharply discontinuous electrical circuit switching, function is effected between the terminals as a result of the deformation of said tube for an amount less than the deformation required to cause the internal opposing peripheral surfaces of the tube to completely abut each other.

References Cited by the Examiner V UNITED STATES PATENTS 2,195,199 3/40 Becker 200-52 2,720,562 10/55 McLaughlin 20 O152,

BERNARD A. GiLHEANY, Primary Examiner. ROBERT K. SCHAEF-ER, Examiner. V I 

1. THE IMPROVEMENT OF A FLUID SWITCH CONSTRUCTION COMPRISING THE COMBINATION OF A SEALED, HOLLOW CONTAINER FORMED OF A VISCOELASTIC, DEFORMABLE MATERIAL, A PLURALITY OF ELECTRICAL TERMINALS SPACED FROM EACH OTHER AND EXTENDING THROUGH SAID CONTAINER INTO ITS INTERIOR HOLLOW PORTION, AN ELECTRICALLY CONDUCTIVE, NON-WETTING FLUID PARTIALLY FILLING THE INTERIOR HOLLOW PORTIONOF SAID CONTAINER AND IN CONTACT WITH ONLY PORTION FOTHE PERIPHERAL SURFACE THEREOF, SAID FLUID BEING IN CONTACT WITH SAID ELECTRICAL TERMINALS SO AS TO PROVIDE A LOW RESISTANCE ELECTRICAL CIRCUIT PATH BETWEEN SAID TERMINALS WHEN THE CONTAINER IS NOT DEFORMED, AND MEANS FOR ENGAGING THE OUTER SURFACE OF SAID CONTAINER FOR DEFORMING THE CONTAINER TO CAUSE THE LOW RESISTANCE ELECTRICAL PATH BETWEEN THE TERMINALS TO BE ABRUPTLY RUPTURED TO FORM A HIGH RESISTANCE OPEN CIRCUIT, THE INTERNAL PERIPHERY OF SAID CONTAINER BEING DEFINED BY A PLURALITY OF ARCUATE SURFACES CONTIGUOUS WITH EACH OTHER AND MEETING AT JUNCTIONS FORMING REGIONS OF SURFACE DISCONTINUITY SUCH THAT A SHARPLY DISCONTINUOUS ELECTRICAL CIRCUIT SWITCHING FUNCTION CAN BE EFFECTED BETWEEN THE TERMINALS AS A RESULT OF THE DEFORMATION OF SAID CONTAINER FOR AN AMOUNT LESS THAN THE DEFORMATION REQUIRED TO CAUSE THE INTERNAL OPPOSING PERIPHERAL SURFACES OF THE CONTAINER TO COMPLETELY ABUT EACH OTHER. 